EXPONENTIAL TRANSMISSION LINE 



571 



resistances instead of the pencil lead. With the fixed IRC resistance it 

 was, of course, impossible to adjust the standard to exactly the same 

 value as the unknown. In this case the small difference was determined 

 by using the slope of the rectifier voltmeter calibration.] This line has 

 a maximum deviation from the desired input impedance of ± 6 percent 

 for all frequencies above 4.2 mc. (Measurements were made up to 28 

 mc.) The phase angle of the input impedance was found to be zero 



10 12 14 16 18 20 22 24 26 28 

 FREQUENCY IN MEGACYCLES 



Fig. 9 — Input impedance characteristics of 15-meter 600 : 300 ohm 

 line of No. 6 conductors 



within the accuracy of measurement. From theory the phase angle 

 would be expected to vary between — 0° and + 3°. 



The curves of Fig. 9 refer to a 600 : 300 ohm line of No. 6 wire 15 

 meters long. With resistance termination this line has rather large 

 variations in the input impedance but with the addition of the proper 

 reactances the input impedance is flatter than the longer line with 

 resistance termination. At the lower frequencies where the variations 

 in the input impedance were large without the reactive networks, their 

 addition gives approximately the expected improvement. At the 

 higher frequencies the inductance was approximately anti-resonated 



